Ultrabright NIR AIEgen nanoparticles-enhanced lateral flow immunoassay platform for accurate diagnostics of complex samples

Accurate and sensitive near-infrared (NIR) luminescent lateral flow immunoassay (LFIA) has attracted considerable attention in the field of point-of-care testing (POCT). However, the detection accuracy and sensitivity are often compromised by the low fluorescence quantum efficiency (<10%) of the NIR fluorescent probe. Herein, ultrabright NIR AIEgen nanoparticles (PS@AIE(830)NPs) composed of polystyrene (PS) nanoparticles and NIR aggregation-induced emission luminogen (AIEgen) with the maximum emission at 830 nm (AIE(830)) is reported, and its potential to promote an accurate and sensitive detection of complex samples by LFIA is described. The relative quantum yield (QY) of the PS@AIE(830)NPs was 14.76%, which was superior to that of the polymer embedding method and indocyanine green (ICG)-based NIR nanoparticles. The PS@AIE(830)NPs immunolabeled-LFIA combined with laboratory-built NIR-LFIA portable quantitative instruments (detected light range > 800 nm) completely eliminated background interference and allowed highly accurate and sensitive detection without any pre-treatment steps. The limits of detection (LODs) for aflatoxin B-1 (AFB(1)) in soy sauce, alpha hemolysin (Hla) of Staphylococcus aureus biomarker in joint fluid, and C-reactive protein (CRP) in human haemolysed samples were 0.01 ng mL(-1), 0.02 mu g mL(-1), and 0.156 mg L-1, respectively, commensurating with those of the corresponding gold standard assays and covering the detection range of interests. It is anticipated that the ultrabright NIR AIEgen nanoparticles will serve as a universally applicable signal probe for NIR-LFIA diagnostics, promising to expand the range of applications for quantitative detection of complex samples.